We used molecular dynamics simulation to study the effect of the external structure on water permeation across a single-walled nanochannel. In contrast with the macroscopic scenario, the outside structure greatly affects the water transport across the nanochannel. Remarkably, the ratio of maximal to minimal flux reached a value of about two for different outside structures. These findings are expected to be helpful in design of high-flux nanochannels and provide an insight into the contribution of the lipid membrane to water permeation across biological water channels.